1. Field of the Invention
This invention relates to rock drilling apparatus, and in particular to the stabilizer assembly for providing lateral support for an unsupported length of drill stem extending upwardly out of the drill hole.
2. Prior Art
Diamond drilling apparatus normally uses a hollow sectionalized drill stem which is subjected to downward pressure as it is rotated so that a bit at the lower end of the drill stem bores into the rock. Circulating water is fed under pressure through the upper end of the drill stem to the bit and serves to cool the bit and deflects the cuttings from the bottom of the hole. As the drill stem follows the bit down the hole, additional lengths of stem are added as may by needed.
In many rock drilling assemblies, the drill stem is embraced by a driven rotatable chuck mounted for vertical travel on a mast and which is capable of remote chucking and de-chucking operations to be carried out during a drilling operation. Due to the heavy downward pressure which must necessarily be applied by the chuck to the drill stem, a tendency of the stem to deflect under load requires that its unsupported length above the drill hole be kept at a minimum. Consequently, this requires a number of chucking and de-chucking operations for each length of drill stem during a drilling operation. Understandably, time taken in a chucking and de-chucking operation is lost time in so far as a drilling operation is concerned.